Question

Jamal watched his older brother Robert lift weights. The bar alone had a mass of 20 kg. on the bar he had two 11.4 weights, two 4.5 kg weights, and four 450 g weights. What mass was Robert lifting?

Answer 1

What you have to do is add them all!
   20   bar
11.4   2 11.4 weights
11.4
  4.5   2 4.5 weights
  4.5
450.0   4 450 weights
 450.0
 450.0
+450.0
---------
        1.8
        10
        200
    +1,600
 --------------
     1,811.8 is the answer